NiO/NiFe2O4 dual-layer coating on pre-oxidized SUS 430 steel interconnect

A Ni/NiFe₂ dual-layer coating is deposited on 50-h pre-oxidized SUS 430 steel by magnetron sputtering for solid oxide fuel cell (SOFC) interconnects application, followed by thermal exposure in air at 800 °C for 1680 h. The thermally grown oxide scales exhibit tri-layer structure with inner Cr₂O₃ layer, middle NiO layer and outer NiFe₂O₄ spinel layer. The oxide coating converted from Ni/NiFe₂ coating not only inhibit the growth of Cr₂O₃ and the outward diffusion of Cr species but also improve the electrical performance of the surface scale. In addition, pre-oxidation treatment for the steel before Ni/NiFe₂ coating deposition prevents the interdiffusion between steel substrate and coating in the oxidation process.